4.2 | Preparation of perfluorocarbon droplets
DPPC and PEG-lipid derivatives of various compositions (8 μmol in total) were dissolved in CH2Cl2. The solvent was evaporated to form a lipid film, which was then suspended in PBS (1 ml) using a bath sonicator to prepare liposomes. After three cycles of freezing in liquid nitrogen and thawing in a water bath (55 °C), 17 μl of PFH was added to the liposome suspension, and the mixture was sonicated on ice using a probe sonicator (UD-200; TOMY Digital Biology Co., Ltd., Tokyo, Japan) to form PFH droplets. After centrifugation (3000 × g ) at 4 °C for 5 min, the supernatant was removed, and the precipitates were resuspended in 20% glycerol PBS solution. This droplet suspension was frozen and stored in a freezer (− 20 °C) until further use.